Maximizing Dynamic Access Energy Efficiency in Multiuser CRNs With Primary User Return

Coexistence between primary users and secondary users (SUs) in a cognitive radio network makes interference inevitable. In coexistence with the dynamic primary user, interference has profound implications on network metrics because the interference due to primary user reoccupancies is intense. To improve the spectrum utilization, mitigating interference should be considered. Hence, in this study, we consider multiuser cognitive radio and propose an analytical framework to formulate dynamic access energy efficiency (DAEE) and collision probability with regard to the traffic behavior of different users. Interferences due to sensing errors and primary user reoccupancies are formulated and introduced in DAEE and collision probability. Network metrics are depicted for different dynamic rates of the primary user traffic and different numbers of SUs. Furthermore, the queue stability of SUs' buffer is also investigated for different numbers of SUs. The effect of sensing and transmission time on the stability area of the SUs' packet queue is discussed too. Finally, simulation results are given to justify the theoretical results. Suitable values for sensing and transmission time are obtained in order to maximize DAEE under collision and queue stability constraints.